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%I #15 Dec 15 2017 17:35:35
%S 170,518,15416,16472,21584,52744,140864,187736,196318,318626,354118,
%T 639286,828814,942326,1333172,1604018,3301024,5240458,6490678,7552264,
%U 8040166,8321326,9790430,12237950,12461834,14818438,19012455,20392318,22625158,29201984
%N Numbers n such that phi(n) = sigma(n) - sigma(n+1).
%H Harry J. Smith and Donovan Johnson, <a href="/A063943/b063943.txt">Table of n, a(n) for n = 1..100</a> (first 39 terms from Harry J. Smith)
%o (PARI) for(n=1, 30000000, if(eulerphi(n)==sigma(n)-sigma(n+1), print1(n,",")))
%o (PARI) { n=-1; t=0; for (m=1, 10^9, s=t; t=sigma(m + 1); if (eulerphi(m)==s - t, write("b063943.txt", n++, " ", m); if (n==38, break)) ) } [_Harry J. Smith_, Sep 03 2009]
%K nonn
%O 1,1
%A _Jason Earls_, Sep 01 2001
%E More terms from _Rick L. Shepherd_, Apr 06 2002
%E Offset corrected by _Donovan Johnson_, Feb 25 2013
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